VOL. LXXXV.] PHILOSOPHICAL TRANSACTIONS. 540 



this means excited. I have also frequently taken hold of a nerve of an animal, 

 which was recently killed, with a non-conductor of electricity, and have in this 

 way applied its loose end to the external surface of the muscle which it entered, 

 without ever observing motion to follow. I think therefore I am entitled to con- 

 clude, not only that the theory advanced by Mr. Galvani, respecting the cause 

 of the muscular motions in his experiments, is erroneous; but also, that the 

 influence, whatever its nature may be, by which they are excited, does not exist 

 in a disengaged state in the muscles and nerves, previously to the application of 

 metals. Should it be urged against this conclusion, that since metals are much 

 better conductors of electricity than moist substances, the charge of a muscle 

 may be too weak to force its way through the latter, though it may be able to 

 pass along the former; my answer is, that in all Mr. Galvani's experiments, the 

 nerve makes a part of the connecting medium between the 2 surfaces of the 

 muscle, and that the power of no compound conductor can be greater than that 

 of the worst conducting substance which constitutes a part of it. 



It may be said however, that though there is no proof that any influence na- 

 turally resides in the nerves or muscles, capable of producing the effects 

 mentioned by Mr. Galvani, these substances may still, by some power inde- 

 pendent of the properties they possess in common with dead matter, contribute 

 to the excitement of the influence which is so well known to exist in them, after 

 a certain application of metals. Before I enter on the discussion of this suppo- 

 sition, I must observe that there are 2 cases of such an application of metals: 

 the first is, when we employ only one metal ; the 2d, when we employ 2 or 

 more. With respect to the first case, a late author. Dr. Fowler, who seems to 

 have made many experiments relative to this point, positively asserts, that he 

 never saw a fair instance of motion bemg produced by the mere application of a 

 single metal to a muscle and its nerve. I shall therefore defer treating this case, 

 till I speak of the conditions which are necessary for the excitement of the in- 

 fluence. Nor will the present subject suffer from this delay; for if it be shown, 

 as I expect it will, that when 2 or more metals are used, the muscle and its nerve 

 do not furnish any thing but what every other moist substance is equally capable 

 of doing, it will I think be readily granted, that they can give nothing more 

 when only one metal is applied to them. 



In regard to the 2d case, Mr. Volta has said, that when 2 metals are employed, 

 the influence in question is excited by their action on the mere moisture of the 

 parts which they touch. The proofs however of this assertion were reserved for 

 some future communication. But as more than 2 years have now elapsed since 

 they were promised, and none have been given to this Society, or have appeared, 

 as far as I can learn, in any other way, I hope I shall not be thought precipitate, 

 if I offer one of the same point, which seems to me both plain and decisive. 



